As a saddle-riding type vehicle of a prior art, for example, patent literature 1 discloses a motorcycle which includes a “normally open” type automatic clutch mechanism (hereinafter referred to as a normally open clutch) in which a clutch is kept released in its normal state where the clutch is not in operation. In the motorcycle including the automatic clutch mechanism, the clutch is driven to be applied and released by an actuator so as to control the transmission of power of an engine to a tire.
In the motorcycle including the automatic clutch mechanism, when an ignition switch is ON, an engine starter motor rotates a crankshaft to a rotation speed at which the engine can be started, and the engine is started by executing an engine start control (ignition and injection).
The engine starter motor is normally driven by a battery and outputs a driving force which can maintain the engine starting rotation speed when there remains a battery capacity which is good enough to do so. However, when the battery capacity is reduced, the driving force of the engine starter motor is reduced, and the rotation speed of the crankshaft cannot be maintained, resulting in fears that it becomes difficult to start the engine.
To start the engine in these situations, so-called “push start” is executed in which a specific gear (other than the neutral and reverse gears) is engaged and a rear wheel, which is a drive wheel, is rotated to obtain a crankshaft rotation speed at which the engine can be started.
To be specific, the rear wheel, which is the drive wheel, is rotated by a rider pushing the motorcycle, and the clutch is applied in this state to connect the rear wheel to the crankshaft. By doing so, the rotation of the rear wheel is transmitted to the crankshaft, and the engine start control is executed when the rotation speed of the crankshaft is raised to the rotation speed at which the engine can be started.